Duller fall colours in Ontario after warmer than normal temperatures

Some parts of Ontario, including the Greater Toronto Area, experienced higher than normal temperatures in September, and that weather pattern leads to duller colours, experts say.

An especially warm fall in Ontario means the province may not get the colourful array of fall foliage that usually transforms treetops this time of year.

Some parts of Ontario, particularly the Greater Toronto Area, experienced higher than normal temperatures in September, and that weather pattern leads to duller colours, experts say.

“The weather that really promotes bright fall colours — strong fall colours — is a combination of sunny and cold, and we have been more sunny and warm,” said Susan Dudley, a professor of biology at Hamilton’s McMaster University.

While temperatures have dropped recently, she said it might be too late for the physiological process that triggers trees to change their colours.

“The weather has been strange, (it) has been very warm up till recently.”

Daylength, tree species and weather conditions are three key factors that determine the colour of autumn leaves, according to experts.

Eastern parts of North America in general, and Ontario in particular, typically have the right combination of these three factors, resulting in vibrant yellow, orange and red foliage, Dudley said.

Ontario’s fall can also be stunning because the province has a longer and colder fall season with enough daylight, and is home to different kinds of woody plants, including maple trees that usually produce beautiful golden and red pigments.